gemini: Bump to kernel v6.1
This bumps the Gemini kernel to use v6.1. While there is no
reason to stay with v5.15, I personally use newer upstream
kernels constantly and they are tested and work well. OpenWrt's
6.1 needs more time until it can be switched.
Signed-off-by: Linus Walleij <[email protected]>
Signed-off-by: Christian Lamparter <[email protected]>